1. Field of the Invention
The invention generally relates to silica nanoaggregates and methods of making silica nanoaggregates. More specifically, the invention relates to the silica nanoaggregates obtained from biomass materials.
2. Description of the Relevant Art
Silica is a very important industrial material and has found widespread applications. In particular, silica nanoparticles with high surface area (porous and/or with a small particle size), are of high interest to many key chemical applications, such as sorption, insulating, sensing, separation, and catalysis. Recently, porous silica for biomedical applications, such as controlled release and biosensing, have also been explored.
Many approaches have been developed to synthesize porous silica and silica nanoparticles. Usually, a silica precursor, such as silicon alkoxide (typically silicon tetraethoxysilane) is used as the silicon source. While such methods are effective to synthesize various silicas with controlled particle size, morphology, and porosity, their main disadvantages are the cost and sustainability issues associated with the silica precursors. Silicon alkoxides are typically synthesized from a multi-step reaction route starting from the carbothermal reduction of raw silica, such as sand. Such chemical processes are energy intensive and associated with high temperature, high pressure, and strong acidity, and thus ecohazardous. Considering the ever increasing demand on porous silica and silica nanoparticles for new applications, the current approach to synthesize porous silica and silica nanoparticles may not be sustainable and not match the cost requirement. Thus, it is highly desirable to seek an alternative approach that is more economical and environmentally benign.